1. Field of the Invention
The invention relates to a setting device for changing the position of a roll with respect to a mating roll. Such a setting device enables the roll to be shifted transversely to its axis in order to bring the roll into contact with a mating roll and press it thereagainst or to move it clear of the mating roll. A preferred field of application for such a setting device is in the wet pressing or smoothing sections of paper making machines. Other applications include calenders for plastics and rolling mills.
2. The Prior Art
U.S. Pat. No. 3,600,273 describes the type of setting device most frequently used for changing the position of a roll. The roll bearings are located in bearing housings. Those housings are arranged on pivoting levers which may be moved by double acting actuator cylinders. Such an arrangement is very elaborate and requires much space.
U.S. Pat. No. 3,885,283 describes a press roll which has a device for adjusting roll flexion. The roll shell supported on a non-rotary beam is able to be set normally in relation to the beam. The mechanism for providing for such adjustability may also be used to move the roll shell clear of the mating roll. One drawback of this system is that if the complexity of manufacture is to be kept within reasonable limits, the adjustment motion is relatively small.
The setting devices in German Unexamined Specification DE-OS No. 2,929,942 and German Unexamined Specification DE-OS No. 3,007,112 call for a stationary bearing housing at each end of the roll. Within the housing, there is a sliding bearing with an associated setting device and linear guide elements. In comparison with the construction of U.S. Pat. No. 3,885,283, the devices of German Unexamined Specification DE-OS No. 2,929,942 and German Unexamined Specification DE-OS No. 3,007,112 provide for large setting strokes. Furthermore, in comparison with the arrangement of U.S. Pat. No. 3,600,273, the amount of space needed for the setting device is small. However, there is the disadvantage that the bearing accommodating the journal and arranged inside the setting device has a much smaller diameter than the external diameter of the rotary roll member. For this reason, it will be seen from FIG. 1 in German Unexamined Specification DE-OS No. 3,007,112 that only the end trunnion of a non-rotary beam is accommodated in the adjustable bearing, whereas the rotary roll shell is bearinged in the end part of the press zone, that is, clear of the setting device, on the non-rotary beam. Another bearing arrangement in many cases is to be preferred to the bearing arrangement in accordance with German Unexamined Specification DE-OS No. 3,007,112. That preferred arrangement, in U.S. Patent No. 4,414,890, may not be accommodated in the setting device of German Unexamined Specification DE-OS No. 3,007,112 because there is not enough space for it.
Furthermore, standard paper making machine rolls (i.e. those without any means for compensating for flexion), which have journals and which are designed for large machine widths, generally require bearings which are so large that they would take up too much space for those bearings to be employed in the setting device of German Unexamined Specification DE-OS No. 3,007,112.
Theoreticaly, it would be conceivable to so enlarge the stationary bearing housing of the setting device of German Unexamined Specification DE-OS No. 3,007,112 that larger moving bearings and their associated actuators might be accommodated in the bearing housing. However, the space available in paper making machinery for the bearing housings is frequently so restricted that it is not possible to increase the size of the bearing housings.